The present invention relates to a rear part structure of a vehicle body and more particularly to a vehicle body rear part structure carrying thereon a fuel tank filled with a gaseous fuel such as hydrogen.
Fuel-cell vehicles are known, which comprise an electric motor rotatably driven by electric energy generated from a fuel cell supplied with hydrogen and oxygen (air). In some known fuel-cell vehicles, a fuel tank filled with hydrogen is mounted on a rear part of the vehicle body for supplying hydrogen to the fuel cell.
One example of such vehicle body rear part structure is disclosed in Japanese Patent Laid-open Publication No. (HEI) 9-300987, entitled xe2x80x9cFuel Tank Supporting Structure for Automobilexe2x80x9d. The disclosed structure includes a chassis frame of rectangular hollow shape attached to a rear portion of a vehicle frame from below. A cylindrical fuel tank filled with fuel gas, left and right suspensions and other parts are attached to the chassis frame before the chassis frame is attached to the vehicle frame.
In the disclosed prior structure, since the fuel tank, suspensions and other parts are previously mounted on the chassis frame so as to form a single module, they can be readily attached at one time when the chassis frame is attached to the vehicle frame. By thus modularizing plural parts, it is possible to improve the productively of the automobile and reduce the size, weight and production cost of the automobile.
The maximum cruising distance of the fuel-cell vehicles depends on the capacity of a fuel tank mounted on the vehicle. In case of the fuel-cell vehicle disclosed in the above-mentioned Japanese publication, a structure is provided to carry a large-capacity fuel tank, thereby providing a long cruising distance. However, in order to improve the ease-of-use of the fuel-cell vehicles, there still exists a demand for a fuel-cell vehicle with structural features which can further extend the cruising distance.
For the fuel-cell vehicles, protection of the fuel tank against damage at a collision is a major requirement. In case of the fuel-cell vehicle disclosed in the aforesaid Japanese publication, damage protection is achieved by placing the fuel tank between left and right body frames. However, further improvements in the damage protection of the fuel tank are desired.
It is accordingly an object of the present invention to provide a vehicle body rear part structure which is capable of extending cruising distance of the vehicle and providing a higher degree of damage-protection to the fuel tank.
To achieve the foregoing object, according to the present invention, there is provided a rear part structure of a vehicle body, comprising: a left rear frame and a right rear frame extending longitudinally of the vehicle body; a support frame of rectangular frame shape attached to the left and right rear frames from below; and at least one cylindrical fuel tank carried on the support frame and having a pipe system connected thereto, Left and right front brackets and left and right rear brackets are disposed, respectively, between front ends of the left and right rear frames and left and right front ends of the support frame and between rear ends of the left and right rear frames and left and right rear ends of the support frame, so as to define between the left and right rear frames and the support frame a pair of laterally aligned of openings generally corresponding in position to the axis of the cylindrical fuel tank and receiving therein the pipe system of the fuel tank.
By thus providing the openings aligned with the axis of the fuel tank and receiving therein the pipe system of the fuel tank, the pipe system is also held safely against damage and the space between the left and right rear frames can be used exclusively for accommodating the fuel tank. Furthermore, the openings may be used for receiving end portions of the fuel tank. This will enlarge the capacity of the fuel tank, leading to an extended cruise distance to the vehicle.
Preferably, the left and right rear brackets extend longitudinally along the rear ends of the left and right rear frames, and a bumper beam is attached to the left and right rear brackets. The bumper beam projects rearward from rear end faces of the left and right rear frames. The left and right brackets have rear end faces offset forwardly from the rear end faces of the left and right rear frames, and the bumper beam is connected to the rear end faces of the left and right rear brackets. With this arrangement, since the rear frames are free from the bumper beam, they can be extended rearward to some extent without changing the overall length of the vehicle body. Due to a mass increased as a result of rearward extension, the rear frames now posses a higher resistance to compressive force when collision occurs at the bumper beam. Thus, the fuel tank is kept safe with a higher degree of damage protection.
It is preferable that the left and right front brackets each have a sloped rear wall extending obliquely upward in a rearward direction of the vehicle body, and the left and right rear brackets each have a sloped front wall extending obliquely upward in a forward direction of the vehicle body. When an impact force is applied to the rear ends of the left and right rear frames, the sloped walls of the front and rear brackets transmit the impact force smoothly and efficiently in the forward direction of the vehicle. By thus transmitting the impact force, the endurance of the rear frames is increased.